Just got my iPad Pro 12.9 Space Grey 256GB. It's bloody brilliant!
The one things that's stands out the most for me compared to my original 12.9 pro is the screen! The 120Hz makes is buttery smooth, the True Tone makes it more pleasant (less blue tint) and miles less reflective. The Apple Pencil is fantastic and writing on it feels much more natural with no noticeable lag in Notes.
Downside? The on screen keyboard in 10.3.2 for some reason feels very laggy but that is minor.
I'm still playing with it . Let me know if you have any questions I'll be happy to help!